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Why US Mileage Ratings Are So Inaccurate
Why does a car rated for 47mpg fall so far short? The Houston Chronicle features an article on just why EPA gas estimates can be so different from real-world drivers' experience at the pump (or in looking at the dashboard display), in particular for hybrid cars. From the article:
"A geometric average of the FTP-75 and HFET results (with city driving weighted at 55 percent and highway driving weighted at 45 percent) produces a vehicle's CAFE fuel economy, which is then incorporated into a manufacturer's corporate average. CAFE is measured using these tests to the present day. In fact, this methodology will be 50 years old when it's used to gauge compliance with the forthcoming 54.5-mpg CAFE requirements in 2025. That kind of continuity is admirable in baseball, but not in transportation. These tests are irrelevant to contemporary real-world driving. For example, the maximum acceleration on either test is 3.3 mph per second. At that rate, it takes more than 18 seconds to hit 60 mph. Even in the horsepower-deprived 1970s, most people were driving harder than that. And the 60-mph maximum speed on the highway test does not accord with the 75-mph truth of today's interstate traffic."
Well obviously - it's because your gallons are smaller than proper gallons.
Its all just a game so they can boost there average and still sell the trucks that have terrible MPG that people want.
Memory is deceptive because it is colored by today's events. - Albert Einstein
Whether those numbers represent a real world mix of driving accurately really doesn't matter all that much, since fuel economy for other driving styles strongly correlates with fuel economy for the conditions that are actually measured. Long term consistency, on the other hand, matters a great deal for car buyers and for evaluating progress on reducing emissions and consumption.
The biggest reason that real-world fuel economy is so different is that the testing is done with a specific "standard" fuel that does not contain any ethanol or other "oxygenator for cleaner burning fuel". The stochiometric ratio required for proper catalitic converter operation on modern cars is maintained by the oxygen sensor adjusting the amount of fuel injected into the engine - too much oxygen in the exhaust gas, add fuel to decrease; too little oxygen, decrease the amount of fuel. This is a closed-loop system that does not take into account fuels that have additional "oxygenators" added - it only cares about the oxygen in the exhaust gas. Add oxygen from fuel additives, reduce oxygen in the exhaust gas by adding more fuel, reduce mileage. "Clean burning fuels" with additional oxygenators is one of the biggest government-mandated ripoffs ever devised. The "testing" done to prove the "value" of oxygenated fuels is done with a single-cylinder carbureted engine in a test lab, with no emission control systems. In the "bench" testing, a specific amount of fuel is burned with the oxygen in the air, and the resulting exhaust gases analyzed for hydrocarbon emissions. Add an "oxygenated" fuel, burn the same specific amount metered at the same air-fuel ratio, and TADA, look, it burns cleaner! Of course it does - there is now additional oxygen in the exhaust gas! But in the real world, the emission systems on a modern car sees the extra oxygen and adds more fuel to the engine to "correct" the air-fuel ratio and reduce the oxygen level in the output gas. They don't tell that part to congress or the consumer, so the use of "oxygenated" fuel is mandated by the law at both federal and state levels - and so 4.) Profit!
And the milage you get on the road does not match the testing...
note: I designed and manufactured fuel control computers for a while, so I know a littile about how things work.
There's plenty to gripe about with the EPA mileage estimates. My personal pet peeve is not accounting for some fuel saving techniques. When I drive in city traffic, especially on my way to work, I spend a substantial amount of time stopped in front of traffic lights. Some cars actually turn off the engine in that scenario. It seems to me that this is a fairly simple optimization to make. Yet many cars don't have this feature. I've been told it doesn't affect the EPA rating, even though real-world fuel savings are reportedly 5-10%.
Please correct me if I got my facts wrong.
When I accelerate slowly (yes, I'm the guy in front of you you regularly curse), drive a pickup with a stick shift and a 2.3 liter four-banger, keep my highway speed to about 60 mph (that's about 90 kph for you metric folks), and use my magic powers to keep the headwinds and crosswinds to a reasonable level my little pickup will get what the EPA said it gets: 29 miles per gallon. I think a lot of it really has to do with how a person drives. Now, in practice I drive a lot faster than that but it's nice to know that the EPA actually got it right.
It's really quite a simple choice: Life, Death, or Los Angeles.
When you are calculating the average of ratios (miles per gallon) and the denominator is the thing that changes, you have to use the geometric mean. If they used liters per 100km, then they would use the regular average.
If your car has an automatic transmission then I would guess that this is due to the way your car's transmission works. I bet you're in a lower gear when you're going 60 than when you're going 75. After all, this is a German car. People driving BMWs, designed to scream on the autobahn. It makes sense that they would gear it to run more efficiently at 75 than at 60.
It's really quite a simple choice: Life, Death, or Los Angeles.
No one cares what the testing procedure is as long as everyone does the same test and it's repeatable. The purpose of the test is to provide a method for consumers to compare different models with respect to their fuel economy, not to provide a precise prediction of exactly what the buyer's fuel economy will be. Everyone drives differently. People warm their car up in the driveway, fill it up with heavy weight, carry lots of passengers, do a lot of long-distance driving, tow trailers, drive up and down hills, ride their brakes, accelerate briskly to beat their neighbor, drive at high altitudes, drive in cold weather, or whatever. Even more significantly, the energy content of 'gasoline' varies widely depending on how much ethanol it has (more is less) and what its boiling point range is. Just do the same test and do it in a way that someone else could repeat the test the same way and get the same result. That's all we need rather it's a 50 year old test or not.
I've only driven 2 cars since the 2008 revision to EPA estimates, but they have been close for me. I drove a Honda Civic Hybrid and got about 47 mpg (EPA estimate 45 mpg). Then, credit shenanigans made most cars unaffordable to me, but I ended up getting a good deal on a 2012 Nissan Altima. With my city driving, I get a little over 20 mpg (EPA rating 23). On long highway trips, I get about 30 mpg (EPA rating 32).
So, with one car, I got a few mpg better than the estimate. With the other, I get a few mpg worse than the estimate. Both of them are close. I do note that both frequent stops and high speed tend to destroy fuel economy. I blame the ridiculous number of stop signs for the former, and drivers' choice to exceed the speed limit for the latter.
Please correct me if I got my facts wrong.
For example, the maximum acceleration on either test is 3.3 mph per second.
It's hard to take a paper seriously when it gets the units of measure wrong.
What's the problem? That *is* an acceleration.
(The SI measure is ms^-2, metres per second squared, or metres per second per second. 3.3 (miles/hour)/second = 0.44704 m s^-2.)
For all the vehicles that I have owned in America, including my current vehicle, I have usually exceeded the EPA estimates except during weeks of especially poor traffic. I consider myself a fairly aggressive driver, especially when compared to the majority of the drivers I see every day.
I think that the EPA estimates are a reasonable "middle ground" but people who drive poorly or inefficiently should not expect to achieve them.
No sig. Move along - nothing to see here.
That all depends on your transmission. Air resistance, gear ratios, etc are all factors that determine the rpm - and that's all that really matters is the rpm. I can do 80 mph and beat the EPA highway ratings on my car by about 3 mpg, as long as it's a fairly steady mph.
"The tree of liberty must be refreshed from time to time with the blood of patriots and tyrants." ~Thomas Jefferson
Why do the numbers not match ?
- huge capacity cylinder (lower consumption ONLY for constant speed driving bad for city profile)
- high horsepower car (requesting power is paid in more fuel burned because this is the power source and the more horse power one can request it will request)
- burnout type
---------
You can drive your 2006 "Nissan Micra 5 gear manual shifting" (http://en.wikipedia.org/wiki/Nissan_Micra) with mileages
from
5.5 L/100km (51.4 miles/galon)
up to
10 L/100km (28.3 miles/galon)
Changing the profile from far commuter to close range commuter with driving inside a city this changes to 6.5 L/100km (44.1 Miles/Galon)
THE PROFILE:
commuter 80km over all 20km countryside / 60km AUTOBAHN (no speed limit)
THE DRIVER:
for operating it with 5.5L/100km you may not exceed (110 km/h) 68 mph
for operating it with 10 L/100km you must go full throttle (ca. 175km/h ) 109 mph
ps.
converting constants
1,609km equals 1iM
4.546L equals 1iG
remark:
it's interesting that EU measures fuel consumption in volume per distance and the "american way" is the invert
- US - higher is better
- EU - lower is better
Um, no. Cars were unmitigated leaded-fuel-guzzling muscle cars (or land yachts, depending on your preference) until the 1973 Yom Kippur War. It would take 20 years of technology before horsepower was restored while keeping MPG high. And as you can see from that linked graph, the 1973's war effects on horsepower were not realized until model year 1977. And since not everyone rushed out to buy new cars at the same time in 1977, that means the vast majority of cars on the road throughout the entire decade of the 1970's were "high" (1990's level) horsepower.
It's those early 1980's cars that were underpowered -- follow-on effects of gas rationing and Nixon price controls.
If you are doing 75mph on the highway you are burning around 20% more fuel to cover the same distance as you would at 60mph
I used to have a car like that.
Now I drive a German one. It idles in sixth gear at that speed.
Schroedinger's Brexit: The UK is both in and out of the EU at the same time!
My Dodge Durango hemi also consistently gets better fuel consumption at higher speed. At 120kmh it runs at only 2000 rpm. I'll probably have to exceed 200kmh before the mileage will get worse.
Excuse me, but please get off my Pennisetum Clandestinum, eh!
Could someone explain this with a car analogy?
rewriting history since 2109
Don't forget, these cars are rated not just for ideal driving habits, but ideal driving conditions. MPG drops drastically once you get over the 60mph mark. My truck gets closest to the EPA rating when I'm doing 60 on highways, but 70-75 on the interstate puts me further from the rating.
Chewbacon
The Bible is like Wikipedia: written by a bunch of people and verifiable by questionable sources.
German cars now violate physics? Was that a dealer option?
the air resistance is nearly doubled at 75 from 60. Pushing air around actually takes up about 40% of a car's energy at highway speeds. Traveling faster makes the job even harder...The increase is actually exponential, meaning wind resistance rises much more steeply between 70 and 80 mph than it does between 50 and 60.
Do not look at laser with remaining good eye.
I think he was talking about the geezers who still think the speed limit is 55 and are sitting in the left hand lane on the freeway. You know, the lane where everyone else is going 80. There are very few left exits, so get your hunk of ancient junk over to the right lane where it belongs.
Peter predicted that you would "deliberately forget" creation 2000 years ago...
If you are doing 75mph on the highway you are burning around 20% more fuel to cover the same distance as you would at 60mph
I used to have a car like that.
Now I drive a German one. It idles in sixth gear at that speed.
And has some magic device to negate the effects of wind resistance?
I was under the impression that the standard unit for fuel consumption in the US is furlongs per hogshead.
You realize that makes almost no sense, right? It typically takes nearly EXACTLY the same fuel to maintain the same RPMs. After having a car with an MPG screen for 10 years, I can assure you that keeping your RPMs low IS efficient driving. They are exactly correlated.
Peter predicted that you would "deliberately forget" creation 2000 years ago...
MPG (miles per gallon) or distance over usage, is not a good way of measuring gas usage. It should be usage over distance.
9900 miles at 33mpfg takes 300 gallons and the same distance at 30mpg takes 330 gallons, note that the difference in usages from high to low is 10%, the lower mpg (30) cars uses 10% more gas than the higher mpg, but it is not correct to say that the 33mpg car uses 10% less gas (more like 9.1% less gas).
Another way is to look at the 75mpg vs 50mpg cars, 7500 miles at 75 mpg takes 100 gallons compared to 150 gallons at 50 mpg.
One way of expressing this difference is to say that the 50 mpg car uses 50% more gas than the 75 mpg car,
another was of expressing this difference is to say that the 75mpg cars uses 33.3% less gas than the 50mpg car.
I bet you're in a lower gear when you're going 60 than when you're going 75.
I doubt it. Every remotely modern (under ten years old) auto car I've ever driven has reached top gear by 60km/h or so (=40ish mph). Unless you put it into "sport" mode, or whatever the equivalent in your vehicle is.
My SUV had a sticker mileage of 15/18, but I get more like 10/14, mostly because of the way I drive. I'm almost always towing something (my boat, my camper, or my utility trailer), or driving 70+ on the highway with a bunch of road bikes and my cargo box on the roof. Worst case is I get about 12 on the highway towing my boat AND having everything on the roof.
Whatever the government thinks my SUV gets for mileage doesn't really concern me, though. The vast minority of people drive their cars the way government thinks they do.
Besides, are any of us really that surprised that government can't get it right?
I'm on my second car which gets its best mileage around 80 mph. It's a 300SD, which does happen to be German. But the prior one was a 240SX. Note that both cars were specifically designed primarily for aerodynamics...
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
that's how the auto industry wants them. The classes/descriptions of vehicles don't make any sense either (SUV's are classed as trucks, not cars) except that it allows the manufacturers to continue to produce gas-hog, mega-polluting vehicles without investing in technology to improve either fuel economy or emissions.
I'm own the much maligned 2013 Fusion Hybrid, and my current tank is averaging about 44 mpg. My work route currently averages between 43 and 50 mpg.
My driving conditions are a mix of heavy suburban traffic and stretch of 25-55 mph interstate, with speeds averaging 15-20 mph during rush our. The terrain is rolling hills, with a delta of about 200 feet.
On a warm (T >70 degree), dry day with no wind and little traffic, the car will easily get the 47 mpg.
Temperature has a large impact on the mpg. The same example above in 25 degree weather will net about 36-38 mpg, consistent with the reporting done over the winter. Obviously, cold starts and running the defroster has a big effect, and the electric traction motor eats away at the battery much quicker at lower temps.
Rain will cut the mpg on my work route to about 43 mpg, and the extra drag is very noticeable. A headwind has the same effect. Tailwinds are fun though, and it kinda feels like sailing when the ICE is off.
Cruising at 55-60 mph on the highway, in no traffic on a warm, dry, and windless day, I can get the 47 mpg.
A quick temperature and mpg plot (assuming dry, windless conditions) looks like:
(T deg F, mpg): (25, 36), (30, 38), (40, 40), (50, 43), (60, 45+), (70, 47+), (80, 45).
There is some roll-off at the higher temps because you have the A/C running.
Driver style has a huge impact on observed mileage, and this cannot be stated enough. My wife is your typical, jackrabbit starting, bumper riding, race-to-red driver. Her mpg is far worse than mine. I doubt she's ever seen 40 mpg. A trip that I can do at 45 mpg, she'll get 36 mpg. I've tried to coach her on the basics of hybrid driving, but she just doesn't get it. I imagine a lot of people are the same way. You either "get" how to drive a hybrid, or you don't.
The statement made was "I bet you're in a lower gear when you're going 60 than when you're going 75".
The point is that most (probably all) modern autos will be in top gear well before 60mph - ie: same gear regardless of cruising speed.
Whether they're designed to be optimal at that speed is an entirely separate issue.
In the whole article it never mentions physically how the vehicles are tested. According to Consumer Reports, they are put on a frictionless "treadmill." There is no way in the world you can get realistic numbers from a frictionless testing device designed to falsify the numbers.
The tests are based on how people should drive as opposed to how almost all people actually drive, that is to say like rude, arrogant, impatient assholes.
There is no "-1 offended" or "-1 you don't agree with me" mod options for a reason.
Because it benefits car companies to have a higher MPG rating.
Most gasoline I can find contains 10% ethanol.
Since ethanol has about 70% of the energy density of gasoline, I would expect to see a 3% loss of fuel efficiency just to start with.
I know I don't get my car's rated MPG just because ... well, I own a car that's fun to drive, so I tend to accelerate a bit faster than I'd bet they test with, and I tend to drive a bit higher than the speed they are likely to test at.
Last time I was in Virginia, I found a gas station that made a big deal about having 100% gasoline (no Ethanol) and I wanted to try filling up with it and seeing if I do indeed get my 3% increase... unfortunately, my tank was already full when I saw it.
The Digital Sorceress
So I wonder, do you thing more accidents are caused by those going below sit speed limits or those going above. it? Think this over, one day you too will live to be one of the geezers that you right now despise. What traffic laws would you propose that protect both the brash young and the conservative elderly that would protect the rights of the most people belonging to such groups?
Time is what keeps everything from happening all at once.
Note that both cars were specifically designed primarily for aerodynamics...
Yeah, different cars are going to have different turbulence and vortexes at different speeds, plus then you have functions of gearing, engine size, etc. which are all going to play into maximum mileage speeds. It might be possible to find an average curve across a range of cars, but individual models will vary widely.
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
First the current 5 cycle EPA test isn't limited to 60mph, it goes up to 80 MPH:
http://www.fueleconomy.gov/feg/fe_test_schedules.shtml
That isn't the real problem. The real problem is that 85% of "EPA Testing" is actually done by the manufacturer themselves. In effect this is a Take home test.
http://www.caranddriver.com/features/the-truth-about-epa-city-highway-mpg-estimates
"While the public mistakenly presumes that this federal agency is hard at work conducting complicated tests on every new model of truck, van, car, and SUV, in reality, just 18 of the EPA’s 17,000 employees work in the automobile-testing department in Ann Arbor, Michigan, examining 200 to 250 vehicles a year, or roughly 15 percent of new models. As to that other 85 percent, the EPA takes automakers at their word—without any testing—accepting submitted results as accurate. "
Since EPA MPG plays a big part in overall advertising campaigns, and potential EPA penalties, there is strong temptation for manufacturers to cheat.
Two years ago Hyundai had an ad campaign featuring how all models of many of it's cars got 40MPG highway without needed special models. Hyundai scored big increase in sales. But later testing a Consumer Reports showed a few of Hyundais models got less than 40 MPG in CR testing. This is ODD because CR testing is more straight forward and the vast majority of cars beat their EPA Highway rating when CR tests them on it's own test. So the CR testing is something of a Sanity check for catching cheaters. Eventually Hyundai was found to have a systemic "mistake" in their testing (AKA cheating). They had to roll back mileage claims across the board and give payouts to customers.
The discrepancy between CR and EPA for Hyundai models before they were caught cheating was 1-3 MPG.
Fords new Hybrids are now falling short by 6-9 MPG and Ford has a new (successful) Ad campaign targeting Toyota, claiming better fuel economy. These new Ford hybrids are the first to make significant sales inroads against Toyota. If anything MPG advertising has even more effect on Hybrid sales.
It isn't hard to see how Fords interests are benefited by high test scores, on a test they administer to themselves, even more than they were for Hyundai before they were caught cheating. It certainly smells like something rotten in Dearborn Mi.
I can explain it with some data regarding my car, a 2011 Kia Sportage. Some would call it a crossover, other would call it a supersized hatchback.
2.4L 176hp four-banger w/ 6-speed transmission. EPA rated it at 21/28. It has an onboard mpg-meter that I've found to be pretty accurate. When cruising on the highway in optimal conditions (no wind, flat terrain, warm weather, inflated tires, etc.), I get:
34 mpg driving 45 mph
32 mpg driving 50 mph
31 mpg driving 55 mph
28 mpg driving 60 mph
27 mpg driving 65 mph
25 mpg driving 70 mph
In addition, the six speed transmission has *barely* enough power to maintain cruising speeds in its highest gear. Any time you accelerate, experience a headwind, go up any hill, drive with a cold car, or have a lot of weight in your vehicle, it doesn't use the highest gear and instead pushes back one or two gears for additional power, dropping your fuel efficiency further.
So, there are considerable variables there that will cause wide variation with highway driving. Grandma and grandpa will be very pleased that they get 32 mpg driving on the highway, while joe leadfoot will probably return the vehicle complaining it only gets 25 mpg (or less) on the highway.
In addition, I only get 12.5 mpg driving in the city. I live in a "city" of 5,000 people. My trek two-and-from work is 2 miles each way. I have six four-way stop signs between here and work. The fastest street I can drive on has a limit of 30 mph. My car is parked outside overnight, and I don't let my car warm up for more than one minute before driving it. Any other city driving is very similar. And that's all why I don't get the EPA-rated 21 mpg in the city.
You realize that makes almost no sense, right? It typically takes nearly EXACTLY the same fuel to maintain the same RPMs. After having a car with an MPG screen for 10 years, I can assure you that keeping your RPMs low IS efficient driving. They are exactly correlated.
your statement about "nearly EXACTLY the same fuel to maintain the same RPMs" is trivially easy to disprove. At 100kpm in 6th gear in my car, I use around 7L/100km (we don't do mpg over here!) going up a hill near my house, and <1L/100km down the other side. RPM's are unchanged up and down that hill, within a few %, and it requires additional fuel to get up the hill, but the injectors basically shut off as I roll down the other side. It's a manual transmission[1] so the RPM's are fixed to the wheel speed for a given gear. My RPM vs wheel speed changes when I change gear, obviously, and while going up a really steep hill I might need to change down to 5th gear (there is such a hill on one of my commutes).
The ideal RPM for your car depends on more factors than you seem to understand. It requires a certain amount of power to push your car along, and that amount of power increases as your speed increases because it's harder to push your car through the air. Ideally you would match your engine speed such that at a given wheel speed the engines use of fuel is optimal to deliver the required amount of power[2]. Your gearbox only allows for fairly coarse adjustements which are a compromise based on expected speed vs power requirements, but generally speaking if you go faster and run out of gears to keep the engine RPM at peak efficiency for that wheel speed then your efficiency will go down, so having an extra gear to "keep the RPMs low" will help.
If your car is geared such that on a nice flat road on a still day (a 40kpm headwind makes a difference here) and you have (say) 5th gear to keep your engine at optimal RPM at 60mph, and 6th gear to keep your engine at optimal RPM at 75mph, then your car _will_ use less fuel at 60mph in 5th than it will at 75mph in 6th. About 20% less. If you go and stick your car in 6th gear at 60mph to "keep the RPMs low", you may well find that your engine is no longer spinning at an efficient speed and your fuel economy will suck. Don't do that.
[1] my gearbox is internally a manual transmission, having a clutch not a torque converter, but the computer controls the clutch and the gear changes (if I let it), I don't have a clutch pedal, so it's listed as an auto even though it has the efficiencies and behaviors of a manual.
[2] 'continously variable' transmissions do exist that can do just that, and while I believe they have inefficiencies of their own they are improving and becoming more common.
I never really considered this but when I think about it, it's true, my Prius doesn't really get the same km/L it should. Shouldn't the car company's be held to the same standard for data as everyone else aka is they lie it's fraud?
I'm on my second car which gets its best mileage around 80 mph. It's a 300SD, which does happen to be German. But the prior one was a 240SX. Note that both cars were specifically designed primarily for aerodynamics...
If you knew how to use the gearbox i bet you could get even better mileage at 60 mph. Either that or the designers of the car are idiots.
The existing disrupting the flow of traffic laws that are nearly never enforced. Geezer doing 55 in the passing lane or kid weaving in and out gets tickets.
No sir I dont like it.
I think your calculation is off. I pulled up one of my favorite utilites, GNU units, to figure out what performance level that is. (This program takes a lot of the guesswork out of dealing with measurements when you live in a country full of Luddites.)
You have: 3.3 mph/s
You want: m/s^2
* 1.475232 <-- this is the actual number
You have: 3.3 mph/s
You want: gravity
* 0.1504318 <-- That's about 1/6 G
You have: 60/3.3
You want:
Definition: 18.181818 <-- Zero to 60
You have: sqrt(.25 mi / ( 0.5 * 3.3mph/s))
You want: s
* 23.354968 <-- Quarter mile
And from litres per 100 km you can then reduce your units and end up with a fuel consumption measured in square millimetres. Volume divided by length gives area.
IIRC, my Smart car used to do about 0.5 mm^2
I worked for just over 2 years in a wind tunnel for a company that manufactured cooling equipment (eg, radiators, oil coolers, A/C condensers and evaporators). We tested products for a variety of manufacturers which meant a wide variety of equipment; ie, compressors, farm tractors, semi tractors, passenger cars, and on one occasion a small city bus to be used in Miami, Florida.
We had a reputation for maintaining a very stable, controlled environment (air flow, heat load, dynamometer load, and positioning of thermocouples for sampling temperatures) and consequently consistent test results.
Now in the interest of full disclosure, this was in the early 70's. But at that time, that's also where the manufacturer's typically got their mileage estimates.
I think this might also be the era from where we get the expression "Your Mileage May Vary" (aka YMMV). I think they included this disclaimer in car ads in an attempt to comply with the "truth in advertising" laws (remember those?).
Clearly nobody can drive a vehicle in a manner as controlled as that.
So if the manufacturers are still getting their mileage results from a wind tunnel test, forget it. You'll never match those results especially if you live in a large metropolitan area (where it's not uncommon to sit idling in traffic) or you live in a mountainous area or where you have really cold weather.
There are several really good comments here with additional insight as to why mileage can vary drastically from the manufacturer's estimate; type of fuel mix, for one.
So remember, when you're buying a car and read those mileage estimates, YMMV.
An effective "democracy" creates the illusion the people have a say in their government.
I'd be very surprised if any of the mileage ratings are accurate. They're all done in laboratory settings simulating very specific things.
Just because your car is rated at xx highway, doesn't mean that's what you'll be getting. It's more of an aid for comparison than accurate ratings.
That being said, it would be nice if the rating had an error bar attached to it. Something like 5.5 l/100 km +/- 0.5 would be helpful
So one level of complaint is that "I get nowhere near the EPA mileage because who drives like that" apart from hyper-miling geeks, old persons, and dudes with a passive-aggressive anti-social attitude. I can see the point, however. Suppose I drive (legally) at 70 MPH and the car is optimized for 50 MPH, how do I read the EPA sticker to find a car that gets OK mileage for the way I drive?
The next level of complaint is that "I am a hypermiling geek, and even I don't get the EPA mileage."
So the question is, is the EPA test even accurate on its own terms?
My limited experience with a Taurus and with a Camry and using a Scan Gauge, if you drive about 10 miles on a 70-deg day without the AC at an average speed of 20 MPH in traffic, you will get better than the derated window sticker and will be within 5% of the "raw EPA numbers." If you drive a constant 55 MPH on a calm wind day, you will get the raw EPA Highway numbers.
The Taurus started to not get the EPA numbers. It turned out to have dragging brakes from rusted caliper pins.
I don't doubt there is cheating, however. I look over the EPA "Test Car List Data" and have seen some fishy drag or coast-down time numbers.
But are people experiencing that if you drive like Granny, some cars get the EPA and o/thers don't? Are there variations between cars of the same model and year, that some engines are manufactured "tight" with much friction and other cars have a natural aptitude for MPG?
FTFS:
Where I live the posted limits are 75 mph. Very few people here drive that slow unless the radar detector is going off or there is a cop actually in view.
The reason I know this is because I *do* drive the posted limit, and I am *constantly* being passed.
And the very *idea* of your typical driver taking 18 seconds to hit 60 mph, or accelerating at such a rate, is hilarious. Near as I can tell, any typical mom-n-pop vehicle, the pedal goes to the floor until the desired speed is hit.
I've fallen off your lawn, and I can't get up.
No, your mileage may vary.
The estimates published by Consumer Reports are pretty good. They very closely match my observed results with a 2007 Honda Accord and 2007 Honda Civic.
I've always gotten better average mileage than the advertised EPA estimates on every car I've owned for the 28 years I've been a licensed driver. (Though on my current car, the discrepancy between actual and EPA is narrower than it was on my older cars.) I suspect that for every person like me, there's a person whose average is lower than the EPA estimate. I'm not sure it's fair to call the EPA estimates "inaccurate." It's more likely that there is a wide margin of error, depending on how well the EPA test matches actual conditions and driving styles. Without knowing the margin of error, it's impossible to determine if the estimates are accurate or inaccurate.
Why aren't "official" MPG ratings accurate you ask? Because almost everyone, except stupid consumers, benefits from this system. The politicians can point to rising average fuel economy, real or exaggerated, that burnishes their green credentials. The environmentalists and their pressure groups don't have to admit that fuel economy isn't going up as much as advertised or even worse "declined" from previous inaccurate measurements. The auto companies are also happy with this fiction because it allows them to continue business as usual which is more profitable for them. In short almost nobody cares about accurate "official" MPG numbers because accurate don't serve the interests of anyone with skin in the game. Consumers who care about the real MPG can find this information with a few Google searches or a visit to one of the consumer review sites where they can pay for detailed reports with the real numbers (often worthwhile when researching a major durable goods purchase). What do you expect out of government? Accurate numbers? The truth? Don't be naive.
There is also something called the harmonic mean, which is more suitable as it is in fact the inverse of the mean of the inverses.
Leaving out the weighting ...
Arithmetic mean: (25 + 40)/2 = 32.50
Geometric mean: SQRT(25*40) = 31.62
Harmonic mean: (2*25*40)/(25+40) = 30.77
(rounded to 2 decimals)
And has some magic device to negate the effects of wind resistance?
It may be magic to you, but the engineers who built my car call it a Bordcomputer. It records trip data and calculates the actual mileage for it. That is what I am interested in anyway. I don't care about the estimated effects of wind resistance. I just want to know my actual mileage. This is what the article is all about: the estimates don't match the actual driving experience.
In my case, I get the best mileage for speeds of 100-110 mph. That's what my friend in the dashboard says, which matches my own calculations.
So, back to effects of wind resistance . . . I guess their effects get canceled out by some other factor of automobile mileage, of which their are many . . . ? More breaking necessary at slower speeds . . . ? (less than 75 mph means the truck lane here) . . . Maybe more acceleration necessary when encountering small hills during the trip . . . ?
I don't know. All that interests me, is the actual mileage. That's it. The rest is just a Milchmädchenrechnung . . .
Note: I am American, but prefer German built cars.
Schroedinger's Brexit: The UK is both in and out of the EU at the same time!
I recently bought a 2013 Impreza with a CV transmission. This car actually exceeds the manufacturer's MPG rating if you let the cruise control do the driving for you. I've hit 49mpg on long stretches of road.
There is a war going on for your mind.
This endangers traffic around them. How is that safe?
I have a relative working in the auto insurance industry - she says that seniors do have the experience to drive safely. But they also drive less. Per kilometre/mile driven, seniors have generally the same amount of accidents as new drivers. Their insurance should reflect this, but it doesn't. Nice that young drivers get penalized, but seniors don't.
lol gaiz Fucked/First On Race Day, Found On Road Dead
'Murica
Acceleration is distance per time per time. The time units don't have to be the same. In this case, it's miles per hour per second -- unusual, but correct.
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While air resistance increases at higher speeds, it doesn't impact fuel economy as much as the gearing in the transmission does. If you compare two otherwise identical cars, the one that allows you to travel at 75 mph @ 2 krpm will get much better fuel economy than the one which has to run at 4 krpm (even though the former will be under higher load). The inefficiency in the engine contributes to more fuel waste than the increased air resistance.
If you want a vision of the future, imagine a youtube comments section scrolling - forever.
Note that both cars were specifically designed primarily for aerodynamics...
Note that both cars were also designed for high speed.
Your average American SUV isn't designed for high speed. Folks ask me if I have problems obeying the speed limits in the US, now that I have experience driving on German Autobahns. The answer: no. When I am on a business trip in the US, and have a rental car, I feel it immediately that the car was not designed for high speed. So I don't drive fast. Easy as that.
The same thing applies to gas mileage. If a certain car was not designed for good mileage at high speeds, it won't get it. And there is no reason for it anyway. If an SUV is primarily used for hauling kids to little league games, it doesn't need to be designed for high speeds. Good mileage in suburban conditions is what people are looking for.
Schroedinger's Brexit: The UK is both in and out of the EU at the same time!
The test should be redesigned, but you all are missing the consequences. You only have so much power in your gas tank, and F = ma means that you really only have a couple good options for improving MPG. There's a limit to how much you can reduce the mass, so manufacturers will start limiting the rate that you can accelerate at. If you have driven a Prius, you know what I am talking about.
Personally, I'm not in a hurry, and I figure time spent accelerating is probably going to be a small component of total travel time. The rest of you should be aware of what you're asking for.
Those who advocate genocide deserve every protection afforded by law, and none afforded by common human decency.
My experience:
I live just outside of Boston.
In trucks I have owned, I get 3-5 mpg less than EPA estimate for both highway and city.
For cars, I get significantly more. In my SAAB 9-3, I average 32mpg combined. On long highway drives I achieve anywhere from 38mpg to 43mpg (depending on whether I open the windows, or the weather; rain decreases it quite a bit)- which is way over EPA estimate. In my ZR-1 Corvette, I achieve 27mpg combined with the stock program, or with the tuner's program (a very aggressive tune) I achieve 22-23mpg. In the city with the stock program, I get 19 - 23 mpg unless traffic is particularly bad, in which case I get 19mpg, and on the highway I get 32mpg (with either program), or over 33mpg at 92mph (I do not drive that fast any more - I like having a clean driving record, but I have been at speeds which see 8mpg in the distant past). I get better highway economy than some friends who drive hybrids, but their city economy slaughters mine.
Years ago I had an MR2 - no matter how I drove it (I was young and arrogant so I drove like a bat out of Hell), I would achieve 37 to 38 mpg combined, regardless of how hard or conservatively I drove that car. Again, well over EPA estimate. I attribute that to shift points and the ultra low mass of the car, and flawed EPA tests of the time, with their fixed RPM shift speeds which do not reflect real-world driving scenarios.
I have a scangauge installed in my SAAB (it won't work in my ZR-1 since it is OBD1, not OBD2 but in that car I use instant MPG to monitor my driving), and I find that accelerating quickly rather than like a snail and choosing shift points carefully makes a huge improvement in economy; I have tried hypermiling techniques in both but I find that trying to shift early and accelerate more slowly significantly increases fuel consumption, so I accelerate somewhat (but not brutally) briskly and shifting a little later results in fantastic economy. In the SAAB it comes down to keeping boost down, and in the ZR-1 it comes down to not opening up the secondary intake manifold and not activating the second bank of fuel injectors (it has 16 fuel injectors, two per cylinder). The hypermiling techniques I use is not braking around turns if I have a clear view, and coasting down hills when the slope is sufficient to overcome drag and friction.
With a manual it comes down to learning the right shift points, and on the highway the best cruise speeds. In my SAAB the best cruise speeds are around 48mph, and around 68 mph, either of which will not get me pulled over in a 45mph or 65mph zone. In my ZR-1, the best cruise speed is 92mph, so I settle for a best of 32mpg on the highway. In both cases I am happy because it significantly decreases the number of fuel stops on road trips, saving a significant amount of time. My favorite vacation spot is in western PA, and in both cars I can drive nonstop there without stopping to fuel up; the only stops are for Starbucks or lunch and nature calls. :-)
I think the reason my trucks were so bad was that both had the entry-level engine which were underpowered six cylinders, so on steep grades the engine would be consuming a lot of fuel to overcome gravity and drag, and coasting down hills wasn't practical unless the grade was significant, so I would never be able to overcome the average incurred going uphill in the first place. Friends with the same model pickups (one of mine was an F-150, the other one was a C1500) with the V8s would actually get better economy than I did, because they did not have to get into the throttle as much, plus I had caps on the trucks all the time because I would often be hauling servers and other electronic equipment, and the caps were a PITA to remove.
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My Gen III Prius is rated for 50 MPG highway. I regularly take extended trips where I get 52-54 MPG. Even my daily highway driving is in that same range, depending on traffic (heavy traffic = less MPG.). Typically the worse I do is 47-48 for combined City/Highway. Of course I can drive like a maniac and get mileage in the low 40's.
http://www.hawknest.com/
Notice how all the commercials now are very careful to say "Em Pee Gee" instead of "miles per gallon". There is a reason for it. "MPG" can mean anything a lawyer can weasel his way into explaining. "Miles per gallon" is a specific measurement that customers could hold car manufactures to.
How quickly you accelerate is almost certainly going to be the biggest factor in fuel efficiency. There are optimizations beyond that, though, as you point out. I adjusted the way I drive after reading this article about hypermilers.
If you drive carefully, you can get mileage that exceeds EPA estimates. If you don't drive carefully, you're probably not saving a lot of travel time, and your mileage is pretty much going to be terrible. You don't need to be Speed Racer every time you sit behind a wheel. Eventually market forces will limit that ability to the privileged class anyway, but until then you're pretty much a douche for speeding.
Those who advocate genocide deserve every protection afforded by law, and none afforded by common human decency.
So I wonder, do you thing more accidents are caused by those going below sit speed limits or those going above it?
Neither is a problem by themselves. It's the difference in speeds that cause problems.
You have: 60/3.3 You want: Definition: 18.181818 <-- Zero to 60
That's why the tests are insanely unrealistic. Even the most underpowered car can manage 0-60 in far less than 18 seconds, and the vast majority of standard sedans will accomplish the task in less than half the time.
I find the tracking my kms on fuelly has led to much more knowledge about how many L/100km I am actually getting, rather than relying on "ideal" conditions. When doing research before buying new cars, it is also nice to have a "real world" database. I used to track using just the trip counter but it turns out that was wildly inaccurate. http://www.fuelly.com/
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Of course they're inaccurate. Do you imagine that anybody in the government or the auto industry believes otherwise?
Politicians want to set minimum MPG so they can win the environmental vote. But actually raising real world MPG is very expensive and puts an artificial constraint on the automotive market: they have to sell cars with more money allocated to MPG and less allocated to whatever it is that the market would otherwise induce them to do. To a certain point most people are comfortable with the government nudging industries in this fashion, as they also do with safety - but the resulting 'standards' are just Emperor's clothes so that all involved can go around patting themselves on the back.
It's a machine that has to be constantly fed, as well. It doesn't matter how many strides the automotive industry made four years ago; every fresh batch of politician needs to bring home fresh victories against Big Corporate America and this is one of them. Of course it's a desirable goal anyway, but by ceding the responsibility for this kind of thing to our elected officials we are telling them that they'll be rewarded for having a dog and pony show about their intentions to one day solve a problem (by which time they will be long gone) and so if we don't care for the resulting disconnect between reality and the pronouncements coming out of where executives are lying in bed with politicians, we have only ourselves to blame.
It's the same thing with health care and online sales taxes. The really big corporations - the ones with large lobbying budgets who can eat added costs - actually want regulatory compliance to be expensive. They've already made huge investments in people whose job it is to satisfy Washington. Small businesses can't do that, so they either go out of business or get bought by bigger business, and the result is that every industry in which the government has a large stake (which is most industries, these days) gets a big barrier to entry and you don't see as many people starting new ventures. That's why start-ups are synonymous with software. Before the ear of 1,000 page regulations passed by a congress that hasn't read it, you had automotive and aviation and energy startups, too. Now these things only happen with lots of money or as second or third ventures for people who have already got that money.
My boss recently bought a 2012 Versa, rated 28/34 if I remember, he is actually getting 22 in the city and around 25 in the freeway and they are slow drivers. He can only get 210-220 miles on a tank, kind of sucks for a small car. On the other hand, I had a 98 subaru wagon, its only rated 18/24 on the new numbers, but I use to get around 30 and 31 a few times with mostly freeway driving, usually around 400 miles on a tank.
Original article: http://www.caranddriver.com/features/why-is-the-epa-so-bad-at-estimating-hybrid-fuel-economy-feature
Mmm, Freetos.
*Still* negative function...
A lot went on in the US automotive world in the 1970's. You started off the with the tail-end of the muscle car era, and by the end of the decade after various government regulations and the fuel crisis scare, you ended the decade with things like the Chevy Chevette, Chrysler K-Cars, and AMC importing the Renaults to the US.. I'd say the horsepower deprived era really started in the mid-late 70's, and went to the mid-80's or so until engine improvements and things like fuel injection and computer controlled timing made it possible to build engines with a decent amount of power and not run into problems with the EPA.
I'm a "hypermiler" and it was natural when I switched from bicycle to car. Perhaps if more people drove in their 20s instead of their teens they would be better drivers.
Driving style has a lot to do with it. I get 10mpg over other people in the same car if I try hard.... and since driving is so dull I may as well keep myself occupied with the road by driving smarter.
Highway limits should be 55mph. maybe 60mph now that cars are more aerodynamic. Above 55mph the majority of your gas is going into PUSHING AIR not propelling you to your destination. Back when 55 was chosen it was the best rate for fuel economy and safety and today it might be 60 or 65 but for safety it's still better at 55.
More people die from cars than bombs or terrorists... but we just won't give up our 5 minutes of time commuting to work... that 5 minutes of savings is just soooo valuable .... except when it is tv commercials... we've let them extend TV advertizing to nearly 8 min out of 30 min... 1/3 and we don't seem to mind losing THAT TIME... (this applies to the 90s before TV was on the internet.)
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I don't get it, 1972 chevy malibu seems to have been introduced in the '60s and has a 300hp option? and late '70s corvettes seem to have 170-220 hp? sounds pretty deprived.
world was created 5 seconds before this post as it is.
My 1984 300TD begs to differ. I'm happy if I make 0-30 in 20 seconds.
I don't suffer from insanity, I enjoy every minute of it! --Longbottle
You're kidding, right?
I wish I could go that fast. Aside from a few trips on open roads, I'm lucky to average about 40 MPH on a freeway commute. And that's the difference between about 14 mpg (at 40 MPH) and 18 mpg (at 80 MPH) for my car.
Have gnu, will travel.
Anybody who drives a 1999-2003 VW Golf or Jetta diesel knows that the then-current EPA tests were EASY to beat for those models, and the now-current EPA tests are absurdly pessimistic. There weren't many competitors to these light models then, and still aren't, but a few are on the way. I suspect today's common rail diesels won't beat the EPA nearly as soundly as the old rotary pump VW TDI diesels did, though.
Whoops, my figure was for 1 mph/second, not 3.3.
I was lazy and used Google. I have GNU units installed, but I forget to use it. It's much better than trying to coax Google into giving the correct conversion.
I forgot then when different cars determine their miles per gallon, the size of a gallon (the denominator) is what changes, not the miles that it can go.
I'm curious about what the equivalent term for "mileage" is.
This is Slashdot. We are geeks. We embrace the scientific method, which includes experimental control.
One knock on the EPA is that they "do a lab test that is never reproduced out on the highway."
What I am saying or suggesting is that driving 55 MPH on a calm wind day without the A/C is a good proxy for the EPA Highway test. I am not saying you have to drive 55 or should drive 55, it is just that there are some stretches of road with a 55 MPH limit that would be a good place to test a car.
So Question 1, what gas mileage do you get driving at 55 MPH on the highway under calm wind conditions, and how does it compare with the EPA test. It's called "experimental control." That is, you first try to see if a car gets anywhere near the EPA gas mileage when driven under as close to EPA conditions as is reasonable for someone without a chassis dyno and an exhaust gas analyser like they have in Ann Arbor, MI at the EPA testing station. If the C-Max and Fusion Hybrid are not getting their EPA numbers, and I am talking the raw numbers and not the "adjusted" numbers on the window sticker, then there is a case to be made that Ford is cheating.
Then Question 2, what gas mileage do you get, say, driving 65 MPH as in the Consumer Reports test? If the C-Max and Fusion do OK at 55 MPH but are not so thrifty at 65 MPH, maybe Ford isn't cheating, but they have optimized those cars for 55 MPH when most people drive 65 MPH (or faster) on the highway. This is an important distinction to us geeks grounded in Experimental Control and the Scientific Method.
So them my Question 3, why doesn't Consumer Reports conduct a road test that best replicates EPA conditions before they start knocking cars for not "living up to the EPA numbers." I don't care about the song, "Pull my license, and all that jive, I . . . can't . . . drive . . . 55!" For cryin' out loud, doesn't Consumer Reports believe in Experimental Control? Report a highway number at a constant 55 and then report a highway number at a constant 65.
Question 4, so why did Consumer Reports change their "highway" road test mid stream? I think they sped up their highway road test to be more consistent with the way their readers drive. Fine. But then you have an apples and oranges comparison between a car built now and maybe a car you owned 30 years ago. Suppose I want to know how a Prius stacks up against the low-tech non-hybrid 1.6 litre 5-speed manual-shift Nova/Corolla I had purchased back in 1986? Can't compare by going through old stacks of Consumer Reports.
As far as it is known, every model of every car maker has to go to Ann Arbor for the original "EPA" drive cycle -- this is for smog control certification, and you extract the EPA City numbers from that, and I think the old "Highway" test is included, both tests used for CAFE regs.
EPA has a new or extended cycle including the high speed highway driving used for the current window sticker. For most cars, they get the "new" sticker numbers be a formula applied to CAFE, but for selected cars, they or the car makers run a full test on them.
With respect to cheating rather than optimizing for or "teaching to the test", EPA relies on the car makers to conduct coast-down or other tests to come up with the drag coefficients to put into the chassis dyno in Ann Arbor. Folks should look up the Test Car List Data (Google for it) for the raw EPA results along with the drag coefficients for the different car models. I am thinking that if we "crowd source" that task, there may be "interesting" findings.
My god! You must be a twenty-something. Or, lived in the country that made the Renault.
Let me introduce you, young sir, to the 1972 Chevy Malibu!
The country that made Renault uses sensible measurements like Kilometres and Litres.
And in the 70's if you didn't have a big car engine it was slow. Even then the big block V8's of the 70's weren't that fast, my 2005 I4 (naturally aspirated) can easily beat them. The small car started to overpower the big car in 80's when you started to get powerful turbo's out of Japan.
Calling someone a "hater" only means you can not rationally rebut their argument.
the air resistance is nearly doubled at 75 from 60. Pushing air around actually takes up about 40% of a car's energy at highway speeds. Traveling faster makes the job even harder...The increase is actually exponential, meaning wind resistance rises much more steeply between 70 and 80 mph than it does between 50 and 60.
And this is why it will save a lot of fuel doing 10 KPH less than the limit...
Because then you can sit behind a lorry and use it as a wind break.
Calling someone a "hater" only means you can not rationally rebut their argument.
During 72-75 or so, they added most of the emissions control systems, and removed lead from gas. So they had to reduce compression, giving some power losses.
However, they also made the horsepower measurement system a little more realistic during this time, so that accounts for a lot of the loss.. prior to 72 or 73, they did the testing on the engines with no/different accessories, different headers/exhaust, etc.
Sent from my PDP-11
Compare Apples to Apples. Your Renault could beat them at what? A 78 Thunderbird with a 351M only had 145 HP but it still had over 275 ft/lb torque under 1800 rpm. It could pull that 4200+ pound car, a family of four and a 5000 pound trailer up a hill.
Erm, I dont have a Renault.
I drive a 2005 Honda Integra Type S. 2.0L inline 4 that puts down 200nm of torque and 160 KW (210 HP) and revs up to 8000 (redline 8100, rev limiter 8300). Towing capacity of 950 KG... but no towbar (it's a sports car). My car only weighs about 1200 KG
However, right now a 2.4 L 4cyl Toyota Econovan could out pull a thunderbird.
But really if you want to frame the argument, try to put that 78 Thunderbird around a corner. You'll manage to get that overweight and underpowered pile of scrap around it by some time next week. Your 0-100 (KPH) times aren't that impressive either.
Calling someone a "hater" only means you can not rationally rebut their argument.
Because the test course is a fixed length and profile, and they're comparing the number of gallons consumed between vehicles to complete the standardised course.
M/g with fixed M and varying g means that the denominator is changing.
It would be difficult to test the cars on a fair yet realistic basis if you had to drive along some kind of (varying) course until you have consumed exactly one gallon and then measure the distance you have travelled.
Volume / distance is a better metric anyway because it's easier to correctly compare the performance of two vehicles. Your fuel savings suffer from diminishing returns from increasing MPG. An improvement from 10 MPG to 20 MPG (halving your fuel consumption) is much, much, much bigger than an improvement from 40 MPG to 50 MPG (cutting your fuel consumption by only 20%). But an improvement of 1 GPM, or 1 L/100 km, is always going to yield the same amount of savings no matter what your baseline is.
This is particularly relevant when you consider that for most use cases, the amount of travel a particular person needs to do is a fixed variable and the type of vehicle they drive (and hence fuel efficiency) is the independent variable. People choose a car based on their needs; they don't select their commuting route based on the kind of car they drive.
You've never driven a honda.
The discussion was about horsepower, not torque. Also torque is a shitty measurement of performance. A vehicle that weighs more is going to produce more torque, but not more performance. A Saab 900i puts 200nm of torque but only 90 KW of power, why, the 900i weighs a ton.
Honda's NA engines have a usable power from 1700RPM to 8000 RPM (9000 in some S2000 models), your big V8's lose power in the higher rev ranges.
Let's take, say, a 1970 challenger. With the lowliest of the low small-block 340, non T/A, did the 1/4 at 14.8 @ 96mph
LoL, My Integra did the quarter mile in 14.7s (stock) and an S2000 can get 14 flat with a semi decent driver. BTW, that 14.7s isn't based on specifications, that's what I've done.
The 8.3L dodge viper V10? Yeah that thing did the 1/4 mile in 11.77 sec @ 123.68 mph.
Lets compare that to a proper V10.
Apple's to Apple's as you say.
A Lamborghini Gallardo LP560 does it in 11.1 at 200KPH.
Sorry if this upsets the fanboy in you, but it takes the top US cars to beat average Japanese and European sports and supercars.
I see why you keep posting as AC, you're embarrassed that you cant drive properly.
Calling someone a "hater" only means you can not rationally rebut their argument.
Just a note - my grandfather willingly gave up his license when he was 94, but even in his late 80's he'd complain about slow people on the road.
"The tree of liberty must be refreshed from time to time with the blood of patriots and tyrants." ~Thomas Jefferson
This is pretty simple really. The accuracy isn't important as every person on the road drives differently and of different roads. The important thing for a mileage rating is that they can be compared from car to car. As long as all the cars follow the same procedure in determining their rating, then you can compare between them. Changing the test will require all the cars to change at the same time. And if you did that you would no longer be able to compare current cars with past cars which some people might like to do when looking at improvement over the years. And even if you did that it would not be accurate anyway as the driving conditions for most people will not match the testing conditions.
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I propose that the Daytona International Speedway set aside four weeks each year for fuel economy testing.
First, each tested vehicle should be driven 40 laps (100 miles) around the circuit at a constant 70 mph, using a very carefully measured quantity of fuel. That will produce the highway mileage rating.
Then, a course laid out in the infield, with sectors of different speeds, stop signs and stop lights, simulated passing zones, etc, would produce an urban cycle fuel economy rating.
The grandstands could be opened to the public, though the testing itself would probably be pretty boring. But at least it would be a transparent procedure and superior to the current problematic methodology.
Ganted people drive and accelerate fast, however, it is not solely the car or driver's fault, some blame can be put on the traffic control systems. I have seen the lights cycle and bring 40-50 cars to a dead stop to let just 2-3 out out on to the parkway.
For cubic inches. None.
The job market is good too! Endemic psychopathic lying.
Americans don't know how to drive.
I get 30 MPG in my 2005 Focus automatic. But my 5 speed Neon got 40.
Fix Or Repair Daily
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